In particular in the case of coating strips, especially metal strips or steel strips, for example using a bonding agent, very thin coatings which are applied by way of a plasma-coating method, for example, are required. A plasma-coating method enables very precise control of the layer thickness, and permits thinnest layers in the nano range to micrometer range to be applied. A plasma-coating device is known from the European patent application EP 2 636 446 A1, for example. By virtue of the plasma-guided coating process, only limited widths of a workpiece to be coated may be processed in the case of plasma coating. Moreover, the application rate is limited such that the strip speed for reaching a specific layer thickness is restricted in the case of coating such that measures for accelerating the coating output have to be taken. Therefore, plasma-coating devices often use a plurality of coating modules, for example more than 5 coating modules, which coat various part-areas of the workpieces to be coated in parallel and/or in series. In the case of coating, in particular in the case of plasma coating, a process gas is supplied to the coating module, and a precursor is injected by way of a pick-off device into the process gas. Herein, the precursor which is prevailing in the supply line of the coating module is entrained by the process gas, is atomized, and is guided together with the process gas onto the surface to be coated. The precursor is the primary material for producing the coating, for example for producing a bonding-agent coating, on the strip surface. To this end, the process gas and the precursor are introduced into the plasma, or into the afterglow of the plasma, respectively. The amount of precursor that is introduced into the process gas depends on the amount of the precursor that is entrained by the process gas in the pick-off device, and thus depends on the precursor level in the pick-off device, or in the supply line to the pick-off device, respectively. In order for continuous coating to be enabled, the precursor level in each pick-off device therefore has to be kept constant, and precursor simultaneously has to be supplied continuously in order for the coating process to be carried out as uniformly as possible.
To date, this issue has been addressed in that a dedicated storage container for the precursor is assigned to each pick-off device of a coating module, the filling of said storage container sufficing, for example, for a complete work shift. However, storing the precursor in a storage container that is assigned to a single coating module has the disadvantage that said storage container has to be individually refilled, this allowing the setting-up times in the case of a multiplicity of coating modules, for example of more than 5, to become excessive. If a plurality of coating modules are to be fed from one storage container, dissimilar line lengths to the coating module, caused by dissimilar flow resistances, lead to dissimilar amounts of precursor being provided such that issues exist in relation to the layer thickness which is applied per coating module. Therefore, identical flow resistances from the storage container up to the individual coating modules would have to be used, in principle. However, the coating device will then become extremely complex, in particular when high production capacities and thus high coating rates or strip speeds are being realized, respectively.